Bashar al-Assad and his wife, Asma, whose personal email addresses and passwords are thought to have been leaked by a government worker. Photograph: Benainous/Hounsfield/Gamma-Rapho via Getty Images

In late March last year, Syrian opposition activists say, a young government worker in Damascus nervously handed a scrap of paper to a friend. On it were four handwritten codes that the friend was instructed to pass to a small group of exiled Syrians who would know what to do with them.

The paper contained two email addresses: sam@alshahba.com and ak@alshahba.com. They are thought to have been the personal email usernames and passwords of the president, Bashar al-Assad, and his wife, Asma.

For the next nine months they were to offer a cell of activists an extraordinary window into what appeared to be the private lives of Syria's first family and their attempts to turn around the country's steady descent towards the abyss.

In June – three months later than the original mole had intended – the email details found their way to two Syrian professionals in a Gulf state. Both had recently become active in the nascent opposition movement in exile after spending most of their adult lives as silent opponents of the regime.

The uprising in the southern Syrian city of Deraa on 15 March had empowered them, as it had hundreds of thousands of others in the totalitarian state. They were now determined to do what they could to bring an end to more than four decades of rule by the Assad clan.

"It was clear who we were dealing with," said one of the activists. "This was the president and his wife. There was no doubt."

At first, the activists say, the emails came in slowly, one or two a day to each account. Assad, as could be expected, was busying himself with affairs of state. His wife was occupied with family life – and shopping.

By the end of the summer, they say, the email traffic to the inboxes had markedly increased. In Assad's case, this coincided with the increase in violence that followed the end of the Muslim fasting month of Ramadan, which last year fell in August.

As 2011 ground on, the situation deteriorated in many parts of Syria. By autumn, Assad had assembled a team of advisers who would help him with the international press and give frank reckonings about sensitive subjects, including the blazing insurgency that had taken hold in Homs and the views of Syria's allies, Iran and Hezbollah.

The media advisers were Sheherazad Jaafari, the daughter of Syria's envoy to the United Nations, Bashar Jaafari, and Hadeel al-Ali, a young Syrian woman studying at a US university.

Both flew to Damascus to advise Assad personally. They demonstrated their contacts in the US by passing on details of conversations with executives from the New York Times, NBC and ABC, all of whom had shown an interest in interviewing the Syrian president.

The two women became regular fixtures in the sam@alshahba.com inbox, with both of them using email addresses that they had used to communicate with journalists and editors.

The activists intensified their efforts as Assad cracked down, monitoring the email accounts 24 hours a day from the comfort of their living rooms.

Some days it was slow going, but the activists were kept enthused by the hope that morsels might arrive that would give them intelligence for use in the field or, better still, help them oust the most impenetrable regime in the Middle East.

They soon noticed differences in the way the couple used their email accounts. "We had to be quick with Bashar's emails," one of the activists said. "He would delete most as soon as they arrived in his inbox, whereas his wife wouldn't. So as soon as they went from unread to read we had to get them fast."

Deleting emails as soon as they arrive shows a degree of awareness of web security. So too did the fact that Assad never attached his name or initials to any of the emails he sent. However, many of the emails that arrived in his inbox are addressed to him as president and contain intimate details of events and discussions that were not known outside of the inner sanctum and would have been very difficult to manipulate.

"We were watching everything closely," the activist said. When Assad was notified about the presence of western journalists in Homs, they were able to warn opposition activists there.

By mid-December, the correspondence to Assad's inbox had become increasingly interesting. There were notes for an election speech he was due to deliver, daily world media briefings, glowing tributes from acolytes and constant chatter from his media advisers. But the devastating revelation that the activists had all been hoping for continued to elude them.

"There was no 800-pound gorilla," one said. "But the body of evidence was still very strong."

In January came the Anonymous leaks: a group of hackers had accessed the Syrian ministry of public affairs website and trawled through more than 80 email addresses stored on the ministry's server. It is suspected that this leak spread the two usernames and password details beyond the small group of activists who were monitoring them. Somehow, someone searching through the ministry's emails was able to establish that the Sam email belonged to the president.

On 7 February, a threatening email in Arabic was sent to the Sam email address. Traffic to the account stopped on the same day. And so did the extraordinary ability to monitor the inner sanctum in real time.

"Now we just want to show the world what this regime is like," said the activist. "We just want him to go."